C++ :: Overload Template Function In A Class?
Jun 21, 2013Firstly, is it legal to overload a template function in a class? This is what I did
class FILE_txt
{
public:
FILE_txt(const char* );
[Code]....
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C++ :: Overload With Template Function
Nov 15, 2013I am a beginner, got confused about:
template<typename T> int compare(T &a,T &b);
int compare(const char *a,const char *b);
char ch_arr1[6]="world",ch_arr2[6]="hello";
compare(ch_arr1,ch_arr2);
After running the code above,we got to know the non-template function is called. What I know is that the array arguments ch_arr1,ch_arr2 will not be converted to char * because the parameters are references in the template functions.
ch_arr1,ch_arr2 need to be converted to const char * if compare(const char *a,const char *b) were called.
I just wanna know what exactly happened behind that? and why?
C++ :: Possible To Overload A Class For Passing To A Function
Feb 1, 2014I want to be able to do
someFunction(MyObject)
rather than
someFunction(MyObject.getWhatIWant())
I know I can do &MyObject, MyObject() and MyObject[0] by overloading operators but is it possible with just plain old MyObject?
this is assuming that I have no access to someFunction(), i.e, it cannot be modified.
C++ :: how To Declare Template Function Inside Template Class
Dec 5, 2013I'm trying to implement a simple template array class, but when i came into the operator< i actually have to use a template :
my code is something like :
template<typename _Type, std::size_t _Size>
class array {
public :
[Code] ......
but i am having an error of shadows template param 'class _Type' is it w/ the name conflict between the array template parameter and the function template parameter ?
C++ :: Using Template Function Inside Class In Separate Function?
Mar 26, 2014i want to use a class to print data stored as vector or array with different data types. i also want the print function two take more than one vector or array or combination of both so that they can be written to file as two columns. so i wrote the following class:
right now it has only one member function for printing two vectors. later i'll add additional functions as required.
note: there has to be template functions inside the class
i also want the object to be global so that i need not pass it as an argument to other calling functions
class printdata
{
public:
template<typename T1,typename T2>
void SaveData( vector<T1> &data1,vector<T2> &data2, std::string var)
{
[Code]....
then i want to call this template function in another ordinary function written in a seperate cpp file
these function declarations are put in a header file. so i need know whether i should put the declaration of the template function in the header to use the function in different functions
C/C++ :: Using Template Function Inside A Class In Separate Function?
Mar 26, 2014i want to use a class to print data stored as vector or array with different data types.
i also want the print function two take more than one vector or array or combination of both so that they can be written to file as two columns.so i wrote the following class:
right now it has only one member function for printing two vectors. later i'll add additional functions as required.
note: there has to be template functions inside the class / i also want the object to be global so that i need not pass it as an argument to other calling functions
class printdata {
public:
template<typename T1,typename T2>
void SaveData( vector<T1> &data1,vector<T2> &data2, std::string var){
std::ofstream myfile;
std::string filename;
[code].....
then i want to call this template function in another ordinary function written in a seperate cpp file these function declarations are put in a header file. so i need know whether i should put the declaration of the template function in the header to use the function in different functions.
C++ :: Function In A Class Template
Mar 3, 2013I have this class templates And This UML.I have to write this function +operator=(source: Array<ElemType, SIZE>): Array<ElemType, SIZE> but I do not know how to start the declaration / or start the function. I have to return a template but I do not know how to do it,
UML
Array<ElemType, SIZE>
-elements: ElemType[SIZE]
+Array()
+Array(source: Array<ElemType, SIZE>)
+operator=(source: Array<ElemType, SIZE>): Array<ElemType, SIZE>
+operator==(other: Array<ElemType, SIZE>): Boolean
+operator!=(other: Array<ElemType, SIZE>): Boolean
<<L-value>>+operator[](index: Integer): ElemType
<<R-value>>+operator[](index: Integer): ElemType
[code]....
C++ :: Template Function Of A Class
Feb 3, 2013I want to use a template function of a class.
This is my code:
#include "Comparison.h"
#include <iostream>
using namespace std;
int main(int argc, char** argv) {
Comparison c;
[Code] ....
But I get the error message:
main.cpp:10: undefined reference to `int Comparison::max<int>(int, int)'
C++ :: Template Function As Member Of Class
Apr 15, 2014I want to have a template function that is a member of a class. Is this possible? This code snippet is how I would think the syntax would go, although it doesn't compile. How would I achieve the same effect?
Code:
class myclass {
public:
int member ;
} ;
template <typename T> void myclass::func( T& arg )
[Code] .....
C++ :: Argument Deduction Of Function And Class Template
Jun 20, 2013When we use a function template, we use a function template like a regular function, for example,
Code:
template<class T>
void foo(T t1, T t2)
{
}
foo(1,3);
Based on the arguments passed to foo, the compiler can deduct the type T. But on the other hand, when we use a class template, we always need to specify the type, for example,
Code:
template<class T>
struct sum {
static void foo(T t1, T t2)
{
}
};
sum<int>::foo(1,3);
Here we can't call sum::foo(1,3), otherwise we get compiler errors. My question is why the compiler can't deduct the type based on the arguments passed to foo? In addition, if we call function template foo like this,
Code:
foo(1, '3');
Then we get compiler errors. We need to specify the type like foo<int>(1.'3'). Since '3' can be always treated as integer, why we need to specify the type here?
C++ :: Passing A Function Pointer As Template Argument To A Class
Aug 15, 2012I have in the past written code for templated functions where one function argument can be either a function pointer or a Functor. Works pretty straightforward.
Now I am in a situation where I am actually trying to pass a function pointer as template argument to a class. Unfortunately this does not work, I can pass the Functor class but not the function pointer. Below code illustrates the issue:
Code:
#include <string>
#include <iostream>
#include <sstream>
#include <cstdlib>
// For demonstration
const char * external_library_call() {
return "FFFF";
[Code] .....
The idea is to have the definition of the Record class simple and readable and have a maintainable way to add auto-conversion functions to the class. So the lines I commented out are the desirable way how I want my code to look. Unfortunately I could not come up with any way that was close to readable for solving this.
C++ :: Error Returning Template Class From Member Function
Apr 30, 2012When I do this:
// header file:
#include <list>
using namespace std;
class myClass {
list<int> myMethod();
};
// cpp file:
list<int> myClass::myMethod() {
}
In the cpp file, 'myMethod' is underlined in red and when I hover over it, it says:
"std::list<int, std::allocator<int>> myClass::myMethod()
Error: declaration is incompatible with "<error-type> myClass::myMethod()""
But when I make it as a standalone function, outside a class, with no pre-declaration, there is no problem.
C/C++ :: Template Class Function Taking A Derived And Generic Object
Feb 23, 2014I'm trying to write a function for receiving messages, so my classes can communicate with each other. The only issue I get is a compile error asking me to define the base parameter as one of the derived instances. I tried using a void* to fill the need, but then I lose the initial type, which I need to check for. How might I go about writing a generic object for this?
Here's my code:
template<class Object>
class State
{
public:
[Code].....
Should I just have all of the objects inherit in the order of Object >> GenericObject >> DerivedObject?
C++ :: Using Template Class - Unable To Match Function Definition To Existing Declaration
May 12, 2013I am just learning using class template but I keep getting error unable to match function definition to an existing declaration
template <typename T>
class Homework {
private:
string name;
public:
template <typename T>
void SetName(T val);
[Code] ....
C++ :: typedef As Data Type For Specialized Template Function In Class From Shared Library
Jul 19, 2013I have a class "Result" with a single template function Set(const std::string& arName, T& val) and a specialization of this function Set<Real>(const std::string& arName, Real& val) where Real is a typedef for double. The class is in a shared library and I use it in my main program. If I do result->Set<GLOBAL::Real>("U", 100.0); the wrong template function is called!
I check this by the output with std::cout.
Maybe it's a problem with the typedef.
If I link the object file of the Result class directly to my main program (no shared library), it works.
typedefs.hpp:
namespace GLOBAL {
typedef double Real;
} results.hpp
#include <iostream>
[Code] ....
C++ :: Force Derived Class To Overload Certain Operators
Dec 14, 2014Is is possible to force derived classed to overload certain operators, like we do with pure virtual functions?
Is this possible to dynamically bind objects to their respective overloaded operators?
I am getting errors with undefined references to my base class vtable when I hackly try to overload: Code: operator+ I am not sure whether this is possible.
C/C++ :: Overload Two Different Operators One Inside Class And Other Outside Using Friend
Nov 23, 2014I'm trying to understand the basics of oop ...
#include <iostream>
using namespace std;
template <typename T>
class max_vector {
private:
T* elemente;
int lungime;
[Code] ....
The purpose of this program is to overload two different operators one inside the class, and the other one outside using friend. The problem is that i get 1 error at the '*' one.
C++ :: Use Of Class Template Requires Template Argument List
Nov 6, 2013Error1error C2955: 'DoubleLinkedListInterface' : use of class template requires template argument listdoublelinkedlist.h10
Error2error C2244: 'DoubleLinkedList<T>::DoubleLinkedList' : unable to match function definition to an existing declaration doublelinkedlist.cpp7
Error3 .cpperror C2244: 'DoubleLinkedList<T>::~DoubleLinkedList' : unable to match function definition to an existing declaration 12
.h
#pragma once
#include "DoubleLinkedListInterface.h"
#include "Node.h"
#include <iostream>
[Code]....
C++ :: Partial Template Specialization With Template Class
May 27, 2013I have a generic template class with another template in one of its types. Now I want to specialize one of its methods for a particular (template) class, which leads to a compile error, however.
Here is the example:
#include <stdio.h>
template<typename Type>
class Obj1 {
public:
void ID() { printf("Object 1, size = %zu
[Code] .....
GCC ends with:
:35:27: error: type/value mismatch at argument 2 in template parameter list for ‘template<class Type, template<class> class O> class Foo’
:35:27: error: expected a class template, got ‘Obj2<Type>’
What is wrong with the specialization? Can it even be achieved and how (if so)?
C++ :: Template With A Specialized Template Class Parameter?
Nov 2, 2014how I want the code to look. Only problem is it doesn't work (Line 11). I have some experience with templates but I'm not a pro.
Basically I want the "Channels<3>" to be a type that I can use to specify a Cable with similar to vector<float/int> it would be Cable<Channels<2 or 3>>.
What have I messed up with the syntax?
#include <iostream>
#include <vector>
using namespace std;
[Code].....
C++ :: Define To Overload Virtual Function
Jul 11, 2014I want to overload pure virtual function from 3rd party SDK class to put my debug messages like that:
errorStatus aXsaction(){printf(_T("
abort transaction"));transactionManager->abortTransaction();}
#define transactionManager->abortTransaction() aXsaction()
But compiler complains on the minus sign:
error C2008: '-' : unexpected in macro definition
Is it possible to trick the compiler?
C++ :: Dealing With Operator Overload Function Failure
Aug 23, 2014Say I have a class that requires dynamic allocation to implement a few of the operators. Take "+" for example; I need to create a new object to hold the sum of the two parameters whose size is not known at compile time.
I'm pretty sure the standard way to indicate a failure inside the overloading function would be to throw an exception. However I am currently involved in an embedded(ish) project where the spec. says no exceptions are to be used.
I think I have 2 options:
1. Return an "invalid" object (with a flag indicating an error has occurred) and check for this after each operation.
a = b + c
if (a.err)
// handle error
or
2. To forsake operator overloading entirely and think up a new way of doing things where all functions that involve dynamic allocation can return error codes. but this seems rather terrible too as I may end up with something like:
objA a
if (add(&a, b, c) == -1) // assuming b and c are initialized before this snippet starts
// handle error
Is there a number 3 that I haven't thought of? It seems that not allowing exceptions is fairly common even in the non-embedded world [URL] so how is this normally done? or is operator overloading usually avoided when exceptions are not allowed?
C++ :: Overload Virtual Member Function In Polymorphism?
Nov 30, 2013I defined a virtual class and three other classes based on it. I want to use them like this:
int main() {
Dirichlet_t D;
Neumann_t N;
Cauchy_t C;
PDEBoundary_t * B1=& D;
PDEBoundary_t * B2=& N;
PDEBoundary_t * B3=& C;
[Code] .....
but I got two major errors
1: "object f abstract type is not allowed" error.-----why not?
2: "the derived class must implement the inherited pure virtual method"-----Did't I?
C/C++ :: Overload Operator With Friend Function Using Constructors
Dec 26, 2014I want to overload prefix and postfix increment(++) operators with friend function. I also have to use the constructors for this. How can I do this? in C++
View 4 Replies View RelatedC++ :: Template Class With Template Members
Feb 9, 2015I have a class like this
PHP Code:
template<class X>
class A {
X m_x;
public:
X* foo();
X* bar();
//others are not related to X
};
I would like to get rid of
PHP Code: template<class X>
For class level but still use it for members. Like this
PHP Code:
class A {
X m_x;
public:
template<class X>
X* foo();
template<class X>
X* bar();
//others are not related to X
};
However, I am still stuck at
PHP Code: X m_x;
C++ :: Write Prototype Of A Member Function To Overload Insertion Operator
Apr 10, 2014Consider the class specification below. Write the prototype (i.e. header) of a member function to overload the insertion operator (i.e. <<). The << operator is to output the data members of an instance of class StudentTestScores into an output stream. Your definition should allow for chaining of output operations (e.g. cout << x << y; where x and y are of type StduentTestScires).
#include <string>
using namespace std;
class StudentTestScores{
private:
string studentName;
float *testScores; // used to point to an array of test scores
int numTestScores; // number of test scores
[code]....